86 THE MICROSCOPE. 
Famiuiarrry wir Eprrruerrum Necessary in BacTeRIoLoGIcaL 
Researcu.*— Barringer thinks that before taking up the study of 
bacteriology it is important that the student should acquire a knowl- 
edge of the different forms of epithelium which are found in various 
portions of the body. 
In the study of the pathogenic bacteria, it might be thought 
that at last there is found one kind of work in which is escaped 
the onus of epithelial tissue detection ; but no, there is no form of 
pathogenic bacteria known that is not ordinarily found associated 
with certain epithelial cells. The gonococcus in the female is mainly 
on the squamous cells from the vagina; in the male, on the cylindrical 
cells of the anterior urethra. The bacillus tuberculosis is, practically 
speaking, always associated with the ciliated epithelium of the 
respiratory tract. The bacillus of Erbeth, as well as the comma 
bacillus of Koch in the dejecta of the bowel, float amongst myriads 
of the cast-off cells of the columnar type. If, then, these cast-off 
histological elements are to be our companions, wherever we go in 
microscopic research, it behooves us to get thoroughly acquainted 
with them. This we can only do by studying them class at a time, 
and observing both their morphological and chemical characteristics; 
for the beginner must know that it is not by looks alone that things 
microscopical are identified, but quite as often by the way in which 
they behave in the presence of certain reagents and stains. It is 
this chemistry of the microscope that has advanced the art in the 
last few years fully as much as has the improvement in lenses. 
Frontan Sac or tHe Muscio#.t—Mr. W. Jenkinson differs 
from Lowne as to the connection of the frontal sac of flies with 
humming.  bBesides the brain, nerves, muscles, air-sacs, etc., the 
head contains a large quantity of fluid, which on coming in contact 
with the inner surface of the sac, would prevent any vibration of its 
walls. He finds from sections that the sac is used as a receptacle of 
tbe fluid contents of the head and proboscis, when the latter is drawn 
up toward and partially into the lower part of the head, emptying 
again as that organ is projected, thus maintaining a uniform pres- 
sure on the nerves, brain and muscles, whatever might be the posi- 
tion of the proboscis. 
Tne Contractite VacuoLte.{—The dispute regarding the nature 
of the contractile vacuole in the protozoa is not at an end. Dr. De 
* North Carolina Medical Journal. 
+ Hardwick’s Science Gossip, December, 1888, p. 265. 
+ American Naturalist, December, 1888. 
